I just found out that one of the guys working for me has had a dead short across 2 phases at the fuseboard, the circuits leading from this board have quite a bit of IT equipment on it, the dead phases wont be turned on until tomorrow but now there worried about the equipment and any possible damage? do we need to worry?

Was it a simple L-L fault, or could N have been involved. I'm just thinking that N will go up to about half Uo (in phase with the faulty L) if there was a L-N fault, so single phase equipment connected to one of the other lines will see the L-N voltage increase somewhat for the duration of the fault.

Large fault currents might induce significant voltages in data cables too - all depending on where they're positioned in relation to the mains cables that carried the fault current.